import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;
-import com.google.common.base.Optional;
import com.google.common.util.concurrent.CheckedFuture;
import com.google.common.util.concurrent.ListenableFuture;
import java.io.IOException;
import java.net.URL;
+import java.util.Optional;
import java.util.concurrent.ExecutionException;
import org.junit.Test;
import org.opendaylight.yangtools.yang.model.api.SchemaContext;